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Miles per hour to kilometers per hour converter

Convert miles per hour to kilometers per hour (mph to km/h) with the exact factor, a conversion chart and worked steps.

Updated Checked against 3 worked examples

mph
Try
Kilometers per hour
km/h
Kilometers per hour: 96.56064 km/h
Shown to 12 significant figures, half-up
Conversion
60 mph = 96.56064 km/h
1 km/h in miles per hour
0.6213711922mph

60 miles per hour is 96.56064 kilometers per hour. Going the other way, 1 km/h is 0.62137119 mph.

Miles per hour to kilometers per hour

05010015020406080100mphkm/h60 → 96.5606
Mph to km/h chart (13 rows)
Miles per hourKilometers per hour
1016.0934
2032.1869
2540.2336
3048.2803
4064.3738
5080.4672
5588.5139
6096.5606
65104.6074
70112.6541
75120.7008
80128.7475
100160.9344
How it's calculated S
  1. Conversion factor

    1 mph=1.609344 km/h1\ \text{mph} = 1.609344\ \text{km/h}

    Exact by definition.

  2. Multiply

    60×1.609344=96.56064 km/h60 \times 1.609344 = 96.56064\ \text{km/h}

About the miles per hour to kilometers per hour converter

A speed in miles per hour may come from a vehicle display or a road sign. Converting the displayed speed is useful when comparing it with a metric scale. It does not change the posted limit or account for speedometer error and changing road conditions.

One mile per hour is exactly 1.609344 kilometers per hour, so 60 mph is 96.56064 km/h. To convert mph to km/h, multiply by 1.609344; to convert back, multiply by 0.6213711922.

One mile per hour is exactly 0.44704 m/s. Because both units are defined exactly, the factor above is exact and the results here carry no conversion error.

Worked examples

60 mph to km/h

Miles per hour (mph)
60 mph
Kilometers per hour
96.56064 km/h

Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

40 mph to km/h

Miles per hour (mph)
40 mph
Kilometers per hour
64.37376 km/h

Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

80 mph to km/h

Miles per hour (mph)
80 mph
Kilometers per hour
128.74752 km/h

Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

Questions

When would I convert mph to km/h?

A speed in miles per hour may come from a vehicle display or a road sign. Converting the displayed speed is useful when comparing it with a metric scale. It does not change the posted limit or account for speedometer error and changing road conditions.

How many kilometers per hour are in a mile per hour?

One mile per hour is exactly 1.609344 kilometers per hour. One mile per hour is exactly 0.44704 m/s.

How do you convert mph to km/h?

Multiply the number of miles per hour by 1.609344. For example, 60 mph × 1.609344 = 96.56064 km/h. To go the other way, divide by 1.609344.

How can I estimate mph to km/h without a calculator?

Multiply by 1.6. That is 0.6% low of the exact factor 1.609344, so 60 mph comes out as 96 km/h instead of 96.5606.

How accurate is the miles per hour to kilometers per hour converter?

Accuracy depends on your inputs and the method's assumptions. Decimal arithmetic uses 50 significant digits, but estimates, numerical methods and source data can be less precise; the displayed rounding does not remove those limits. It is checked against 3 worked examples whose answers come from independent sources; for example, “60 mph to km/h” is checked against Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions).

Where does the method come from?

NIST SP 811 (2008), Guide for the Use of the International System of Units, Appendix B; NIST Handbook 44, Appendix C: General tables of units of measurement; BIPM, The International System of Units (SI Brochure), 9th edition.

About this calculator

kilometers per hour=miles per hour×1.609344\text{kilometers per hour} = \text{miles per hour} \times 1.609344

Sources

  1. NIST SP 811 (2008), Guide for the Use of the International System of Units, Appendix B
  2. NIST Handbook 44, Appendix C: General tables of units of measurement
  3. BIPM, The International System of Units (SI Brochure), 9th edition

Checked against references

3 worked examples with independently sourced answers ship with this calculator. They run in the test suite; you can run them here too.

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